Polyester film and subbing layers therefor



United States Patent 3,495,984 POLYESTER FILM AND SUBBING LAYERS THEREFOR Johannes Camiel Vanpoecke, Berchem-Antwerp, Lodewijk Felix De Keyser, Mortsel-Antwerp, and Andre Jan Conix, Antwerp, Belgium, assiguors to Gevaert Photo-Producten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Continuation of application Ser. No.

572,188, Aug. 15, 1966, which is a continuation-inpart of application Ser. No. 243,664, Dec. 10, 1962. This application Nov. 25, 1968, Ser. No. 778,860 Claims priority, application Belgium, Dec. 11, 1961, 41,206, Patent 611,358 Int. Cl. G03c l 80, 3/26 US. Cl. 9687 11 Claims ABSTRACT OF THE DISCLOSURE A multilayer photographic film in which the light-sensitive silver halide emulsion layer is attached to a biaxially stretched polyester film support by means of a gelatin subbing layer underlying the emulsion layer and an intermediate subbing layer formed of a mixture of cellulose triacetate and a polyester of at least one phthalic acid and at least one aliphatic diol, the polyester being soluble in chlorinated aliphatic hydrocarbons. The mixed intermediate subbing may be replaced by two successive layers, one comprised of the specified polyester and the other formed of cellulose triacetate.

The present invention relates to photographic film elements comprising a light-sensitive silver halide emulsion layer and particularly to such elements comprising a biaxially stretched poly(ethylene terephthalate) film support, this application being a continuation of application Ser. No. 572,188, filed Aug. 15, 1966, now abandoned, which is a continuation-in-part of application Ser. No. 243,664, filed Dec. 10, 1962, now abandoned.

Such film elements are used more and more, because they are exceptionally stable against all kinds of external influences and have a high dimensional stability. Especially and latter characteristic is of considerable importance for many applications. However, it is not easy to find appropriate subbing layers for adhering the silver halide emulsion layer to the biaxially stretched poly(ethylene terephthalate) support.

A first object of the present invention is to provide suitable subbing layers for adhering a light-sensitive silver halide emulsion layer to a biaxially stretched poly(ethylene terephthalate) support, said subbing layer assuring a good adherence before, during, as well asafter processing of the photographic film element in the photographic baths.

A second object of the present invention is to provide a photographic film element, which on processing manifests no appreciable coloration, due to an interaction between the sensitizing dyes, which are present in the silver halide emulsion layer, and the subbing layers.

A third object of the present invention is to provide a photographic film element, from which the emulsion layer does not get loose nor crumbles away on heating, a heat treatment being a step to which the element is subjected in many applications.

3,495,984 Patented Feb. 17, 1970 These and further objects can be accomplished by consecutively applying the following subbing layers between the biaxially stretched poly (ethylene terephthalate) support and the light-sensitive silver halide emulsion layer of a photographic film element:

A layer comprising cellulose triacetate and a polyester of at least one phthalic acid and at least one aliphatic diol, said polyester being soluble in chlorinated aliphatic hydrocarbons, and

A layer for adhereing the silver halide emulsion layer to cellulose triacetate.

According to another embodiment the polyester cellulose triacetate subbing layer can be replaced by a first subbing layer of said soluble polyester and a second subbing layer of cellulose triacetate applied thereto.

It is known for a long time to use polyesters or polyester-type compounds in the manufacture of subbing layers.

From the United States patent specification 2,096,616 it is known to use polybasic acid-polyhydric alcohol resins as material for subbing layers on a cellulose triacetate film support. However, this type of polyesters is not suited for constituting a subbing layer on a biaxially stretched poly(ethylene terephthalate) support because it is repelled by the latter.

In the United States patent specification 2,698,239the same type of polyester subbing layers as those applied according to the present invention are disclosed. According to the method of said specification, however, the polyester subbing layer is applied to a poly(ethylene terephthalate) support, a gelatino silver halide emulsion layer or first a gelatin layer and then the gelatino silver halide emulsion layer being applied afterwards to the subbing layer. According to the present invention the gelatino silver halide emulsion layer or a gelatin subbing layer can only be applied if cellulose triacetate is used first either incorporated into a separate subbing layer or incorporated into the polyester subbing layer.

From the United States patent specification 2,874,046 it is known to use subbing layers for a poly(ethylene terephthalate) film support, the film-forming agent of said subbing layer essentially consisting of a polyester of an a,,8-ethylenically unsaturated aliphatic dicarboxylic acid and certain glycols. In a specific example given hereinafter it is shown that this type of polyesters is less suited than the polyesters used according to the present invention.

Finally, the subbing layers applied according to the present invention have the advantage over the subbing layers of the film element according to the Belgian patent specification 604,869 of causing little or almost no coloration due to post-development interaction with sensitizing dyes often applied in light-sensitive silver halide emulsion layers. Especially the sensitizing dyes described in the French patent specifications 1,137,701, 1,239,318 1,223,- 289 and 1,278,009 should be mentioned in this respect. A comparative test as to said coloration between a photographic film element according to the present invention and a photographic film element according to said Belgian patent specification is described hereinafter.

According to the present invention the soluble polyester and the cellulose triacetate are preferably applied to the 'biaxially stretched poly (ethylene terephthalate) support in a single layer. In this case, the most important problem is to find a common solvent for both substances.

Suitable solvents, which can be used alone or in combination with each other are: acetone, methylene chloride, chloroform, ethylene chlorohydrin, ethylene dichloride, alcohols, etc. Some of these solvents, however, are less suited than others. So it has been found that the polyester-cellulose triacetate layer when applied from a pure methylene chloride solution has a rather mat appearance and when applied from a pure chloroform solution possesses less favorable adhering characteristics.

Experiments prove the favorable use of ethylene dichloride, as swelling agent for the cellulose triacetate, in the solution from which the polyester-cellulose triacetate subbing layer is to be coated. Particularly good results have been obtained when using a combination of ethylene dichloride with methylene chloride.

The polyester and the celluose triacetate may be present in a common layer in different ratios but preferably in such a way that for each gram of cellulose triacetate the amount of soluble polyester varies between 0.16 and 2 g.

The thickness of the polyester-cellulose triacetate subbing layer depends on the purpose, the film element was intended for, but preferably varies between 1.2 and 2.5

It is also possible to coat separately on the biaxially stretched poly (ethylene terephthalate) film support a first subbing layer of soluble polyester and thereupon a layer of cellulose triacetate. In this case the thickness of the polyester layer preferably amounts to 1.2 to 2.4,u. and the thickness of the cellulose triacetate layer to 1.0 to 15 The polyester is preferably coated from low-boiling chlorinated aliphatic hydrocarbons. Suitable solvents from which the cellulose triacetate can be applied, are chlorinated aliphatic hydrocarbons e.g. methylene chloride, carbon tetrachloride, sym-tetrachloroethane and 1,1,2-trichloroethane. As to the cellulose triacetate, use can be made of cellulose triacetates having different molecular weights.

The polyesters of at least one phthalic acid and at least one aliphatic diol may be of a widely different nature, if only they are soluble in chlorinated aliphatic hydrocarbons. The polyesters may be derived from terephthalic acid, isophthalic acid and/ or phthalic acid. In the preparation of the polyesters other recurring acid units may be present as well. Aliphatic saturated dicarboxylic acid units are interesting in this respect. More particulars on suitable polyesters can be found in the Belgian patent specification 611,224. Aliphatic diols suited for the preparation of the polyesters are mentioned in this specification and specific examples of suitable polyesters as well as their preparation are given as well. Briefly, stated, such suitable polyesters include the following:

A polyester of isophthalic acid and at least one aliphatic diol,

A polyester of isophthalic acid, terephthalic acid and at least one aliphatic diol,

A polyester of isophthalic acid, at least one aliphatic saturated dicarboxylic acid in an amount of at most 20% by weight of the total amount of acid, and at least one aliphatic diol, and

A polyester of isophthalic acid, terephthalic acid, at least one aliphatic saturated dicarboxylic acid in an amount of at most 20% by weight of the total amount of acid, and at least one aliphatic diol.

On the polyester-cellulose triacetate layer or on the cellulose triacetate layer a layer is coated for adhering the silver halide emulsion layer on cellulose triacetate, in other words, a layer known to be a good subbing layer for hydrophilic colloids constituting the binder of the silver halide emulsion layer, preferably a gelatino silver halide emulsion layer is coated on cellulose triacetate.

Sui able subbing layers for hydrophilic colloids on cellulose triacetate are described in the British patent specification 617,129, in the German patent specification 1,040,898, and in the Belgian patent specifications 601,- 390 and 601,393. G latin subbing lay s are used preferably for this purpose. This gelatin subbing layer is preferably applied from a dispersion of gelatin in a mixture of water, acetone and alcohol generally taken in the following ratio: from 12 to 23 parts by volume of water, from 45 to parts by volume of acetone and the remainder till 100 parts by volume being alcohol. In addition thereto, small amounts of acid are required for keeping the gelatin suspended in organic solvents. The most appropriate acids are 'maleic acid, salicylic acid, nitric acid, toluene sulfonic acid, oxalic acid, itaconic acid and tartaric acid. The thickness of such gelatin subbing layer preferably ranges from 0.3 to 0.611..

Further details on the biaxially stretched poly (ethylene terephthalate) film support and the light-sensitive silver halide emulsion layer will not be given since these kinds of materials are generally known to those skilled in the art of photography.

Some specific examples illustrating the present invention and showing the advantage of the present subbing layers over the subbing layer already referred to above Will now be given hereinafter.

EXAMPLE 1 A biaxially stretched poly(ethylene terephthalate) support of 100, in thickness is overcoated with a first subbing layer from the following solution:

Cellulose triacetate g 1.25 Poly(ethylene isophthalate) g 0.3 Mixture of ethanol, ethylene dichloride and methylene chloride (10/35/55) cm. 25 Ethylene dichloride cm.

This layer is coated in such a way that 1 liter covers 15 sq. m.

The layer is dried for 5 minutes at 75 C. A second subbing layer can then be applied from the following coating composition:

A common non-sensitized gelatino silver halide emulsion layer is applied to this gelatin layer.

The emulsion layer adheres very well to the biaxially stretched poly(ethylene terephthalate) support as well before as during and after processing of the photographic material.

EXAMPLE 2 To a biaxially stretched poly(ethylene terephthalate) support of 12014 in thickness, provided with a first subbing layer as described in Example 1, a second subbing layer is applied from the following coating solution:

Gelatin g 1 Salicylic acid 0.2 Chrome alum g 0.015 Water cm. 20 Acetone cm. 45 Ethanol cm. 35

This layer is coated in such a way that 1 liter covers 45 sq. m.

The support provided with said subbing layers is then coated with a silver halide emulsion layer as described in Example 1. The photographic material thus obtained possesses the same properties as the material described in Example 1.

EXAMPLE 3 On a poly( ethylene terephthalate) support as described in Example 1 a first subbing layer is coated from the fol lowing coating solution so that 1 1. covers 17 sq. m. of support:

Cellulose triacetate g 1.25 Poly(ethylene isophthalate) g 1 Mixture of ethanol, ethylene dichloride and methlyene chloride (10/35/55) scm. 25 Ethylene dichloride cm. 35 Methylene chloride cm. 40

This first layer is dried for 5 minutes at 75 C. A second gelatin subbing layer as described in Example 1 is then coated thereon.

The support provided with said subbing layers is coated with a silver halide emulsion layer as described in Example l. The photographic material thus obtained possesses the same properties as the material described in Example 1.

EXAMPLE 4 Example 3 is repeated, with the proviso, however, that the first subbing layer is coated from the following composition in such a way that 1 1. thereof covers 15 sq. m of support:

Cellulose triacetate g 1.25 Poly (ethylene isophthalate terephthalate) (5 0) 5 g 0. Mixture of ethanol, ethylene dichloride and methylene chloride (/35/55) cm. 25 Ethylene dichloride cm. 75

The resulting photographic material possesses almost the same good properties as the material described in Example 3.

EXAMPLE 5 On a poly (ethylene terephthalate) support as described in Example 1, three subbing layers are consecutively coated from the following compositions:

Poly(ethylene isophthalate) g 10 Ethylene dichloride cm. 100 1 l. of this composition covers 40 sq. m. of support.

Cellulose triacetate g 1.25 Mixture of ethanol, ethylene dichloride and methylene chloride (10/35/55) cm. 25

Methylene chloride cm. 37.5 Ethanol cm. 20 1,2-propane diol cm. 10 Ethylene chlorohydrin cm. -7.5 l l. of this composition covers sq. m. of support.

Gelatin g 1 Maleic acid u g 0.1 Chrome alum g 0.01 Water cm. Acetone cm. 50 Ethanol cm.

l l. of this composition covers sq. m. of support.

After having been coated, each subbing layer is dried for 5 minutes at 75 C. To this subbed biaxially stretched poly(ethylene terephthalate) support a non-sensitized gelatino silver halide emulsion layer is applied.

A good adhesion between the support and the emulsion layer is obtained before, during, as well as after treatment in the photographic baths.

EXAMPLE 6 A first lot of samples of light-sensitive material is manufactured by applying consecutively to a poly(ethylene terephthalate) support as described in Example 1 a polyester layer and a cellulose nitrate gelatin layer as described in Example 1 of the Belgian patent specification 604,869 and by applying a silver halide emulsion layer to these subbing 6 layers. Material A is prepared with a non-sensitized emulsion. Material AI is prepared with an emulsion, which is sensitized with a compound corresponding to the following structural formula:

I ?-CH2 v CCH CHCH=C CH Bl 1130-0 2 C 2H5 C2H5 Material All is prepared with an emulsion, which is sensitized with a compound corresponding to the following structural formula:

Material AIII is prepared with an emulsion, which is sensitized with a compound corresponding to the following structural formula:

SCH2 CH2-O-CO c 03 A second lot of samples of light-sensitive material is manufactured by consecutively applying to a poly(ethylene terephthalate) support as described in Example 1 different subbing layers.

A first subbing layer is applied from the following composition:

1 l. of this composition covers 15 sq. m. of support.

A second layer as described in Example 1 is coated on this first layer. On the second layer a common silver halide emulsion layer is coated for each of the materials B, BI, B11, and E111 to be prepared.

Material B is prepared from a non-sensitized emulsion. The materials BI, B11 and E111 are prepared with emulsions which are sensitized with the foregoing compounds 1, 2' and 3 respectively.

These 8 materials are treated in photographic baths. It is found that the materials A and B are colorless, whereas all other materials show a more or less residual coloration due to the action of the sensitizer on the combination of subbing layers. All these materials are examined photospectrometrically. A curve, which is charac teristic for each material, is obtained. This curve is plotted in a diagram of percent of transmittance against wavelength. The curves of A and B have a regular course, viz. without minimum or maximum, Whereas the other curves show a minimum of transmittance, for a determined wavelength of the incident light, which is defined by the kind of sensitizer. When the transmittance of a material AI, for example, shows a minimum of y% at a wavelength X and the transmittance of material A is 1% at a wavelength X, then z%y% is an indication for coloring of material AI. In the same way one can proceed with the materials All and AIII in respect of material A and with the materials BI, BH and BIlI in respect of the material B. When these results of the materials AI, A11, A111 are compared with the results of the materials BI, BII and BIII respectively, one can see which subbing layer in a material, which is identical in other respects, gives the smallest residual coloration.

The percent of transmittance of material AI in respect of the percent of transmittance of material A in the maximum absorption region of the material AI (i.e. 515 III/b), is 8% lower. When this result is represented by:

then the following results are obtained:

AI BI =e15 m,u)=8% (=515m.-=)=

It appears from these comparative tests that a quite considerable improvement as to coloration is obtained when using the subbing layers according to the present invention instead of the subbing layers according to the Belgian patent specification 604,869.

EXAMPLE 7 A biaxially stretched poly(ethylene terephthalate) support of 100g in thickness is overcoated with a first subbing layer from a solution of 0.5 g. of poly(ethylene isophthalate) and 1.2 g. of cellulose triacetate in a solvent mixture composed of 30 ccs. of a mixture of methylene chloride and ethyl alcohol (90/10), 40 ccs. of ethylene dichloride and 30 ccs. of methylene chloride. After drying of the first subbing layer a second gelatin subbing layer and a gelatino silver halide emulsion layer are applied thereto as described in Example 1.

Four further photographic film elements are prepared in an identical manner, each of them comprising another type of polyester in an amount of 0.8 g. per 100 ccs. of solvent mixture for the first subbing layer.

In the first element poly(ethylene isophthalate/phthalate) (20/80) is used as polyester.

In the second element poly(ethylene isophthalate/terephthalate) (50/ 50) is used as polyester.

In the third element poly(ethylene terephthalate/isophthalate/adipate) (10/ 80/ 10} is used, and in the fourth element a polyester of terephthalic acid, maleic anhydride, and ethylene glycol the preparation of which is described in Example 1 of the above mentioned U.S.P. 2,374,046 is utilized.

The emulsion layer of each of the five photographic film elements thus obtained shows a sufiicient adherence to the biaxially stretched poly(ethylene terephthalate) support before, during, as well as after processing of the photographic film elements.

When, after complete processing i.e. after rinsing and drying, the five photographic film elements are kept for minutes at a temperature of 100 to 110 '53., no significant alteration can be noticed in the first 4 photographic film elements. However, in the fifth, i.e. the element comprising the polyester according to the USP. 2,874,046, in the first subbing layer, a frilling of the emulsion layer can be seen at the edges of the film element. This disadvantageous characteristic manifests itself in practice especially when projecting and copying on which case the photographic element is sometimes heated considerably.

We claim:

1. A photographic filrn element comprising consecutively;

a biaxially stretched poly(ethylene terephthalate) supa layer consisting essentially of cellulose triacetate and a polyester of at least one phthalic acid and at least one aliphatic diol, said polyester being soluble in chlorinated aliphatic hydrocarbons,

a gelatin layer for adhering the silver halide emulsion layer to cellulose triacetate, and

a silver halide emulsion layer.

2. A photographic film element according to claim 1, wherein the polyester of the polyester cellulose triacetate layer is a member of the group consisting of:

a polyester of isophthalic acid and at least one aliphatic diol,

a polyester of isophthalic acid, terephthalic acid and at least one aliphatic diol,

a polyester of isophthalic acid, at least One aliphatic saturated dicarboxylic acid in an amount of at most 20% 'by weight of the total amount of acid, and at least one aliphatic diol, and

a polyester of isophthalic acid, terephthalic acid, at least one aliphatic saturated dicarboxylic acid in an amount of at most 20% by weight of the total amount of acid, and at least one aliphatic diol.

3. A photographic film element according to claim 1, wherein the silver halide emulsion layer is a gelatino silver halide emulsion layer.

4. A photographic film element according to claim '1, wherein the polyester cellulose triacetate layer has a thickness of 1.2 to 2.5].t.

5. A photographic film element according to claim 1, wherein the polyester cellulose triacetate layer contains 0.16 to 2.0 parts of said polyester per part of cellulose triacetate.

6. A photographic film element comprising consecutively:

a biaxially stretched poly(ethylene terephthalate) support,

a layer consisting essentially of a polyester of at least one phthalic acid and at least one aliphatic diol, said polyester being soluble in chlorinated aliphatic hydrocarbons,

a cellulose triacetate layer,

a gelatin layer for adhering the silver halide emulsion layer to cellulosetriacetate, and

a silver halide emulsion layer.

7. A photographic film element according to claim 6, wherein the polyester of at least one phthalic acid is a member of the group consisting of:

a polyester of isophthalic acid and at least one aliphatic diol,

a polyester of isophthalic acid, terephthalic acid and at least one aliphatic diol,

a polyester of isophthalic acid, at least one aliphatic saturated dicarboxylic acid in an amount of at most 20% by weight of the total amount of acid, and at least one aliphatic diol, and

a polyester of isophthalic acid, terephthalic acid, at least one aliphatic saturated dicarboxylic acid in an amount of at most 20% by weight of the total amount of acid, and at least one aliphatic diol.

8. A photographic film element according to claim 6 wherein the silver halide emulsion layer is a gelatino silver halide emulsion layer.

9. A photographic film element according to claim 6, wherein the layer comprising a polyester of at least one phthalic acid and at least one aliphatic diol has a thickness of 1.2 to 2.4 1. and the cellulose triacetate layer has a thickness of 1.0 to 1.5,u.

A photographic film element according to claim 1, wherein the polyester of the polyester cellulose triacetate layer is poly(ethylene isophthalate).

3,495,984 9 10 11. A photographic film element according to claim 6 2,874,046 2/1959 Klockgether et a1. 96-87 wherein the polyester of at least one phthalic acid and at 3,178,287 4/ 1965 Sweet et a1. least one aliphatic diol is poly(ethylene isophthalate).

NORMAN G. TORCHIN, Primary Examiner References Clted 5 R. H. SMITH, Assistant Examiner UNITED STATES PATENTS 2,096,616 10/1937 Nadeau 96-87 -C -XR. 2,698,239 12/1954 Alles et a1. 96-87 117-34, 76 

